rewrite the expression -3a(a+b-5)+4(-2a+2b)+b(a+3b-7) to find the coefficients of each term

Expanding, we have

-3a^2 -3ab + 15a - 8a + 8b +ab +3b^2 -7b       And combining like terms

-3a^2 +7a -2ab +3b^2 + b